applications: nrf5340_audio: Added high CPU load print

Using the high CPU load monitoring feature, print a message using printk
when the CPU load exceeds a defined threshold.

OCT-3414

Signed-off-by: Kristoffer Skøien <[email protected]>

Author: koffes

applications/nrf5340_audio/prj.conf

@@ -79,3 +79,11 @@ CONFIG_BT_ATT_TX_COUNT=12
 
 # Suppress the USB deprecation warning
 CONFIG_DEPRECATION_TEST=y
+
+# Log high CPU load using printk
+CONFIG_CPU_LOAD=y
+# Disable LOG_PRINTK to ensure printk messages are displayed even under high CPU load,
+# by preventing them from being processed by the logging subsystem.
+CONFIG_LOG_PRINTK=n
+CONFIG_CPU_LOAD_LOG_PERIODICALLY=5000
+CONFIG_CPU_LOAD_LOG_LEVEL_WRN=y

applications/nrf5340_audio/src/utils/peripherals.c

@@ -14,13 +14,19 @@
 #include "sd_card.h"
 #include "nrf5340_audio_dk_version.h"
 #include "device_location.h"
-
 #include "sd_card_playback.h"
 
+#include <zephyr/debug/cpu_load.h>
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(peripherals, CONFIG_PERIPHERALS_LOG_LEVEL);
 
 static struct board_version board_rev;
+#define CPU_LOAD_HIGH_THRESHOLD_PERCENT 98
+
+static void cpu_load_cb(uint8_t percent)
+{
+	printk("CPU load high: %d %%\n", percent);
+}
 
 static int leds_set(void)
 {
@@ -153,5 +159,11 @@ int peripherals_init(void)
 		return ret;
 	}
 
+	ret = cpu_load_cb_reg(cpu_load_cb, CPU_LOAD_HIGH_THRESHOLD_PERCENT);
+	if (ret) {
+		LOG_ERR("Failed to register CPU load callback");
+		return ret;
+	}
+
 	return 0;
 }

doc/nrf/releases_and_maturity/releases/release-notes-changelog.rst

@@ -178,7 +178,13 @@ Wi-Fi®
 Applications
 ============
 
-|no_changes_yet_note|
+nRF5340 Audio
+-------------
+
+* Added high CPU load callback using the Zephyr CPU load subsystem.
+  The callback uses a :c:func:`printk` function, as the logging subsystem is scheduled out if higher priority threads take all CPU time.
+  This makes debugging high CPU load situations easier in the application.
+  The threshold for high CPU load is set in :c:file:`peripherals.c` using :c:macro:`CPU_LOAD_HIGH_THRESHOLD_PERCENT`
 
 Connectivity bridge
 -------------------